Observational evidence of cloud processes contributing to daytime elevated nitrate in an urban atmosphere

Tao, Jun; Zhang, Zhisheng; Tan, Haobo; Zhang, Leiming; Wu, Yunfei; Sun, Jianqi; Che, Huizheng; Cao, Junji; Cheng, Peng; Chen, Laiguo; Zhang, Renjian

doi:10.1016/j.atmosenv.2018.05.040

Cited by 37 publications

(13 citation statements)

References 31 publications

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“…In comparison, the MMADs of SO 2− 4 in the coarse mode were in between of those of Ca 2+ and Na + , likely due to uptake of H 2 SO 4(g) by both mineral dust and sea salt particles (Zhang et al, 2015a). In contrast, the MMAD of NH + 4 in the coarse mode was 3.25 ± 0.69 µm, much smaller than those of SO 2− 4 and NO − 3 , suggesting that NH + 4 in the coarse mode was likely from hygroscopic growth of NH + 4 in the droplet mode (Tian et al, 2014).…”

Section: Water-soluble Inorganic Ionsmentioning

confidence: 96%

“…To investigate the formation of haze, the original and revised IMPROVE formulas have been directly applied in many cities in China (Hua et al, 2015;Shen et al, 2014;Tao et al, 2009;Zhang et al, 2012a;Zou et al, 2018). The IMPROVE formulas have been proven to overestimate or underestimate b sp in urban cities in China (Cao et al, 2012;Cheng et al, 2015;Han et al, 2014;Jung et al, 2009a, b;Tao et al, 2012Tao et al, , 2014, which was likely due to the significantly different size distributions of the major chemical components and related mass fractions in PM 2.5 between different countries or even individual cities (Bian et al, 2014;Cabada et al, 2004;Chen et al, 2017;Guo et al, 2010;Lan et al, 2011;Tian et al, 2014;Yao et al, 2003;Yu et al, 2010;Zhang et al, 2008;Zhuang et al, 1999b). To reduce the uncertainties in the estimated b sp using the original and revised IMPROVE formulas, the average MSEs of the dominant chemical species were typically estimated by the multiple linear regression method (Hand and Malm, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou in southern China

Tao

Zhang

et al. 2019

Atmos. Chem. Phys.

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Abstract. To grasp the key factors affecting particle mass scattering efficiency (MSE), particle mass and number size distribution, PM2.5 and PM10 and their major chemical compositions, and the particle scattering coefficient (bsp) under dry conditions were measured at an urban site in Guangzhou, southern China, during 2015–2016. On an annual average, 10±2 %, 48±7 % and 42±8 % of PM10 mass were in the condensation, droplet and coarse modes, respectively, with mass mean aerodynamic diameters (MMADs) of 0.78±0.07 in the droplet mode and 4.57±0.42 µm in the coarse mode. The identified chemical species mass concentrations can explain 79±3 %, 82±6 % and 57±6 % of the total particle mass in the condensation, droplet and coarse mode, respectively. Organic matter (OM) and elemental carbon (EC) in the condensation mode, OM, (NH4)2SO4, NH4NO3, and crustal element oxides in the droplet mode, and crustal element oxides, OM, and CaSO4 in the coarse mode, were the dominant chemical species in their respective modes. The measured bsp can be reconstructed to the level of 91±10 % using Mie theory with input of the estimated chemically resolved number concentrations of NaCl, NaNO3, Na2SO4, NH4NO3, (NH4)2SO4, K2SO4, CaSO4, Ca(NO3)2, OM, EC, crustal element oxides and unidentified fraction. MSEs of particle and individual chemical species were underestimated by less than 13 % in any season based on the estimated bsp and chemical species mass concentrations. Seasonal average MSEs varied in the range of 3.5±0.1 to 3.9±0.2 m2 g−1 for fine particles (aerodynamic diameter smaller than 2.1 µm), which was mainly caused by seasonal variations in the mass fractions and MSEs of the dominant chemical species (OM, NH4NO3, (NH4)2SO4) in the droplet mode. MSEs of the dominant chemical species were determined by their lognormal size-distribution parameters, including MMADs and standard deviation (σ) in the droplet mode.

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Section: Water-soluble Inorganic Ionsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou in southern China

Tao

Zhang

et al. 2019

Atmos. Chem. Phys.

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“…At this sampling site, an in-situ gas and aerosol composition monitor (IGAC/S-611) was used to measure the water-soluble ions (SO 4 2-, NO 3 -, and NH 4 + ) in PM 2.5 on an hourly basis. Previous studies have verified the accuracy of such monitoring through comparison with the commonly used annular denuder system, and the results showed good agreement (Young et al, 2016;Tao et al, 2018). Hourly concentrations of OC and EC in PM 2.5 were monitored using a Sunset Laboratory Model-4 OC-EC field analyzer with detection limits of 0.4 µg C m -3 for OC and 0.2 µg C m -3 for EC.…”

Section: Observational Datamentioning

confidence: 78%

Formation and Evolution Mechanisms of Severe Haze Pollution in the Sichuan Basin, Southwest China

Yang

Lü

Zhu

et al. 2020

Aerosol Air Qual. Res.

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Severe haze episodes are important environmental issues, and the rapid formation and evolution mechanisms of such episodes over complex terrain remain poorly understood. The Sichuan Basin (SCB) periodically experienced heavy haze pollution during the winter of 2016, with the maximum regional average PM 2.5 concentration reaching almost 120 µg m-3. In this study, we characterize a severe haze episode in the SCB from 20 to 30 January 2017 using comprehensive measurements and model analyses. The evolution of this severe episode shows clear stages, with gradual PM 2.5 increases under stagnant weather conditions in Stage I (aerosol accumulation stage) and with explosive PM 2.5 increases mainly associated with cross-border transport from the southern SCB in Stage III (rapid formation stage). The process analysis results indicated that primary emissions and aerosol processes were the major sources of PM 2.5 in these urban regions, whereas vertical transport and dry deposition generally acted as sinks of PM 2.5. In the presence of southwesterly synoptic winds, the aerosols emitted from the southern SCB were transported to Chengdu and the surrounding areas through horizontal transport and accounted for 66% of the PM 2.5 concentration in Chengdu during Stage III. Our results reveal the detailed formation mechanism of a severe haze episode in the SCB under the effects of regional transport and synoptic forcing patterns to improve the understanding of haze formation in areas with complex terrain.

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“…Besides, high relative humidity (~78% and 80% in average) was measured respectively during the autumn and winter measurement periods in Guangzhou. The contribution of droplet mode sulfate was higher at 488 m than that at two lower levels, leading to the conclusion that in-cloud or aerosol droplet processes is likely the main formation pathways for sulfate with evidences of frequent cloud coverages at 500-1000 m above the ground in urban Guangzhou measured using a ceilometer during the measurement periods (Tao et al, 2018).…”

Section: Vertical Distribution Of the Major Chemical Compositionsmentioning

confidence: 98%

Vertical distribution of atmospheric particulate matters within urban boundary layer in southern China: size-segregated chemical composition and secondary formation through cloud processing and heterogeneous reactions

Zhou

Guo

et al. 2019

Preprint

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Abstract. Great progress has been made recently in the understanding of the sources and formation mechanisms of atmospheric aerosols at the ground level. However, vertical profiles and sources of size-resolved particulate matter within the urban boundary layer are still lacking. In this study, vertical distribution characteristics of size-segregated particles were investigated at three observation platforms (ground, 118 m and 488 m) on the 610-meter-high Canton Tower in Guangzhou, China. Size-segregated aerosol samples were simultaneously collected at the three levels on the Canton Tower in autumn and winter, respectively. Major aerosol components, including water-soluble ions, organic carbon and elemental carbon, were measured. The results showed that daily average fine-particle concentrations generally decreased with height. Concentrations of sulfate and ammonium in fine particles displayed small vertical gradients and nitrate concentrations increased with height in autumn, while the above chemical components showed greater variations in winter than in autumn. The size distributions of sulfate and ammonium in both seasons were characterized by dominant unimodal droplet modes with a peak at the size range of 0.44–1.0 μm. In autumn, the nitrate size distribution was bi-modal, peaking at 0.44–1.0 μm and 2.5–10 μm, while it was unimodal in winter, implying that the formation mechanisms for nitrate particles were different in the two seasons. Our results suggest droplet mode sulfate and nitrate are likely formed from aqueous-phase reactions and coarse mode nitrate formation is attributed to heterogeneous reactions of gaseous nitric acid on existing sea-derived coarse particles in autumn at the measurement site. The results from pollution cases study further showed that atmospheric aqueous-phase and heterogeneous reactions together with adverse weather conditions, such as temperature inversion and calm wind, resulted in the autumn and winter haze pollution in the PRD region.

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Observational evidence of cloud processes contributing to daytime elevated nitrate in an urban atmosphere

Cited by 37 publications

References 31 publications

Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou in southern China

Impact of particle number and mass size distributions of major chemical components on particle mass scattering efficiency in urban Guangzhou in southern China

Formation and Evolution Mechanisms of Severe Haze Pollution in the Sichuan Basin, Southwest China

Vertical distribution of atmospheric particulate matters within urban boundary layer in southern China: size-segregated chemical composition and secondary formation through cloud processing and heterogeneous reactions

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